Display module and head-mounted display device therewith

ABSTRACT

A display module includes a plurality of light-emitting elements and a sealing element sealing the plurality of light-emitting elements. The sealing element includes a base part including a transparent material and a cover layer. The cover layer is in contact with a surface of the base part and includes a plurality of first patterns, each of which is engraved in an intaglio manner to a first depth, and a plurality of second patterns, each of which is engraved in an intaglio manner to a second depth different from the first depth.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority under 35 U.S.C. § 119 to KoreanPatent Application No. 10-2018-0161050, filed on Dec. 13, 2018, thedisclosure of which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

Exemplary embodiments of the present inventive concept relate to adisplay module and a display device including the display module, andmore particularly, to a head-mounted display device worn on a user'shead.

DISCUSSION OF THE RELATED ART

A head-mounted display device is a display device worn on user's headthat may provide augmented reality or virtual reality content to theuser. A head-mounted display device for realizing augmented realityprovides a virtual graphic image displayed on a semitransparent displayto a user. In this case, the user can view not only the virtual graphicimage, but also a real object at the same time (e.g., the virtualgraphic may be superimposed over the real object). A head-mounteddisplay device for realizing virtual reality provides a virtual graphicimage to a user's eyes.

A screen-door effect (SDE) is a certain type of noise pattern which maybe recognized by a user viewing a head-mounted display device. The SDEmay also be called a fixed pattern noise. The SDE may arise from adifference in luminance between center and peripheral regions of alight-emitting element in each pixel. Due to the SDE, a boundary betweenpixels may be recognized by a user, thus deteriorating display quality.

Since the head-mounted display device provides a wider field of view toa user compared with a typical flat-panel display device, thehead-mounted display device may be more vulnerable to deterioration indisplay quality caused by the SDE.

SUMMARY

An exemplary embodiment of the inventive concept provides a displaydevice configured to suppress a screen-door effect (SDE), and ahead-mounted display device therewith.

According to an exemplary embodiment of the inventive concept, a displaymodule includes a plurality of light-emitting elements and a sealingelement sealing the plurality of light-emitting elements. The sealingelement includes a base part including a transparent material and acover layer in contact with a surface of the base part. The cover layerincludes a plurality of first patterns, each of which is engraved in anintaglio manner to a first depth, and a plurality of second patterns,each of which is engraved in an intaglio manner to a second depthdifferent from the first depth.

In an exemplary embodiment, the cover layer includes silicon dioxide.

In an exemplary embodiment, the plurality of first patterns and theplurality of second patterns are alternatingly disposed.

In an exemplary embodiment, a thickness of the base part may range fromabout 100 μm to about 300 μm, a thickness of the cover layer may rangefrom about 500 nm to about 600 nm, and each of the first depth and thesecond depth may range from about 100 nm to about 200 nm.

In an exemplary embodiment, the second depth is larger than the firstdepth, and a difference between the second depth and the first depthranges from about 70 nm to about 90 nm.

In an exemplary embodiment, the cover layer further includes a pluralityof third patterns, each of which is engraved in an intaglio manner to athird depth different from the first depth and the second depth. Thethird depth ranges from about 100 nm to about 200 nm.

In an exemplary embodiment, a largest difference between the firstdepth, the second depth, and the third depth ranges from about 70 nm toabout 90 nm.

In an exemplary embodiment, the plurality of first patterns, theplurality of second patterns, and the plurality of third patterns arealternatingly disposed.

In an exemplary embodiment, each of the plurality of second patterns isdisposed between one of the plurality of first patterns and one of theplurality of third patterns.

In an exemplary embodiment, an inner side surface of the cover layerdefining at least one of the plurality of first patterns and theplurality of second patterns is inclined at an angle of about 60° toabout 85° relative to the base part.

According to an exemplary embodiment of the inventive concept, a displaymodule includes a plurality of light-emitting elements, and a sealingelement sealing the plurality of light-emitting elements and including abase part including a transparent material and a cover layer disposed ona surface of the base part. The cover layer includes a base layer incontact with the surface of the base part, a plurality of firstpatterns, each of which protrudes from the base layer by a first length,and which are spaced apart from each other by a first distance, aplurality of second patterns, each of which protrudes from a portion ofa corresponding one of the plurality of first patterns by a secondlength, and a plurality of third patterns, each of which protrudes fromanother portion of a corresponding one of the plurality of firstpatterns by the second length.

In an exemplary embodiment, each of the plurality of second patterns isspaced apart from a corresponding one of the plurality of third patternsprotruding from a same first pattern by a second distance.

In an exemplary embodiment, the cover layer includes silicon dioxide.

In an exemplary embodiment, a thickness of the base part ranges fromabout 100 μm to about 300 μm, and a thickness of the base layer rangesfrom about 250 nm to about 400 nm. The first length ranges from about 70nm to about 90 nm, and the second length ranges from about 10 nm toabout 130 nm.

In an exemplary embodiment, a side surface of each of the plurality offirst patterns or a side surface of each of the plurality of secondpatterns is inclined at an angle of about 60° to about 85° relative tothe base layer.

According to an exemplary embodiment of the inventive concept, ahead-mounted display device includes a display module including aplurality of light-emitting elements and a sealing element sealing thelight-emitting elements, and a body portion containing the displaymodule. An opening is defined in the body portion that exposes at leasta portion of the display module to a user. The head-mounted displaydevice further includes a strap portion connected to the body portionand configured to fix the body portion to a head of the user. Thesealing element includes a base part including a transparent materialand a cover layer in contact with a surface of the base part. The coverlayer includes a plurality of first patterns, each of which is engravedin an intaglio manner to a first depth, and a plurality of secondpatterns, each of which is engraved in an intaglio manner to a seconddepth different from the first depth.

In an exemplary embodiment, the cover layer includes silicon dioxide,and the plurality of first patterns and the plurality of second patternsare alternatingly disposed.

In an exemplary embodiment, a thickness of the base part ranges fromabout 100 μm to about 300 μm, a thickness of the cover layer ranges fromabout 500 nm to about 600 nm, and each of the first depth and the seconddepth ranges from about 100 nm to about 200 nm.

In an exemplary embodiment, the second depth is larger than the firstdepth, and a difference between the second depth and the first depthranges from about 70 nm to about 90 nm.

In an exemplary embodiment, the cover layer further includes a pluralityof third patterns, each of which is engraved in the intaglio manner to athird depth different from the first depth and the second depth. Thethird depth is larger than the first depth and is smaller than thesecond depth.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the inventive concept will become moreapparent by describing in detail exemplary embodiments thereof withreference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a display device according to anexemplary embodiment of the inventive concept.

FIG. 2 exemplarily illustrates a user wearing the display device shownin FIG. 1 .

FIG. 3 exemplarily illustrates a body portion, a cushion portion, anddisplay modules of the display device shown in FIG. 1 .

FIG. 4A illustrates an exemplary planar structure of a portion of adisplay module according to an exemplary embodiment of the inventiveconcept.

FIG. 4B is a cross-sectional view taken along line I-I′ of FIG. 4A.

FIG. 5 is an enlarged view of region ‘AA’ of FIG. 4B.

FIGS. 6A and 6B are graphs exemplarily showing a change in luminance ofa pixel region caused by a variation in depth of an intaglio pattern ina cover layer.

FIGS. 7 and 8 are cross-sectional views each illustrating an example ofa modified structure of region ‘AA’ of FIG. 5 .

FIG. 9 illustrates an exemplary planar structure of a portion of adisplay module according to an exemplary embodiment of the inventiveconcept.

FIGS. 10 and 11 are cross-sectional views taken along line I-I′ of FIG.4A.

It should be noted that these figures are intended to illustrate thegeneral characteristics of methods, structure and/or materials utilizedin certain exemplary embodiments and to supplement the writtendescription provided below. These drawings are not, however, to scaleand may not precisely reflect the precise structural or performancecharacteristics of any given embodiment, and should not be interpretedas defining or limiting the range of values or properties encompassed byexemplary embodiments. For example, the relative thicknesses andpositioning of molecules, layers, regions and/or structural elements maybe reduced or exaggerated for clarity. The use of similar or identicalreference numbers in the various drawings is intended to indicate thepresence of a similar or identical element or feature.

DETAILED DESCRIPTION

Exemplary embodiments of the present inventive concept will be describedmore fully hereinafter with reference to the accompanying drawings. Likereference numerals may refer to like elements throughout theaccompanying drawings.

It will be understood that when a component, such as a film, a region, alayer, or an element, is referred to as being “on”, “connected to”,“coupled to”, or “adjacent to” another component, it can be directly on,connected, coupled, or adjacent to the other component, or interveningcomponents may be present. It will also be understood that when acomponent is referred to as being “between” two components, it can bethe only component between the two components, or one or moreintervening components may also be present. It will also be understoodthat when a component is referred to as “covering” another component, itcan be the only component covering the other component, or one or moreintervening components may also be covering the other component. Otherwords use to describe the relationship between elements should beinterpreted in a like fashion.

It will be understood that, although the terms “first”, “second”, etc.may be used herein to describe various elements, components, regions,layers and/or sections, these elements, components, regions, layersand/or sections should not be limited by these terms. These terms areonly used to distinguish one element, component, region, layer orsection from another element, component, region, layer or section. Thus,a first element, component, region, layer or section discussed belowcould be termed a second element, component, region, layer or sectionwithout departing from the teachings of exemplary embodiments.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

As used herein, the singular forms “a,” “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise.

Exemplary embodiments of the inventive concept are described herein withreference to cross-sectional illustrations that are schematicillustrations of idealized embodiments (and intermediate structures) ofexemplary embodiments. As such, variations from the shapes of theillustrations as a result, for example, of manufacturing techniquesand/or tolerances, are to be expected. Thus, exemplary embodiments ofthe inventive concept should not be construed as limited to theparticular shapes of regions illustrated herein but are to includedeviations in shapes that result, for example, from manufacturing, aswould be understood by a person having ordinary skill in the art.

Herein, when one value is described as being about equal to anothervalue or being substantially the same as or equal to another value, itis to be understood that the values are equal to each other to within ameasurement error, or if measurably unequal, are close enough in valueto be functionally equal to each other as would be understood by aperson having ordinary skill in the art. For example, the term “about”as used herein is inclusive of the stated value and means within anacceptable range of deviation for the particular value as determined byone of ordinary skill in the art, considering the measurement inquestion and the error associated with measurement of the particularquantity (i.e., the limitations of the measurement system). For example,“about” may mean within one or more standard deviations as understood byone of the ordinary skill in the art. Further, it is to be understoodthat while parameters may be described herein as having “about” acertain value, according to exemplary embodiments, the parameter may beexactly the certain value or approximately the certain value within ameasurement error as would be understood by a person having ordinaryskill in the art.

FIG. 1 is a perspective view of a display device HMD according to anexemplary embodiment of the inventive concept. FIG. 2 exemplarilyillustrates a user US wearing the display device HMD of FIG. 1 .

Referring to FIGS. 1 and 2 , the display device HMD may be ahead-mounted display device, which can be worn on a head of the user US.The display device HMD may provide an image to the user US whilepreventing the user US from seeing through his or her peripheral vision.Since the user's peripheral vision is blocked, the user US wearing thedisplay device HMD may be more immersed in virtual reality contentprovided via the display device HMD.

The display device HMD may include a body portion 100, a strap portion200, a cushion portion 300, and display modules DM-L and DM-R (e.g., seeFIG. 3 ).

The body portion 100 may be a portion corresponding to eyes of the userUS. The body portion 100 may be configured to contain the displaymodules DM-L and DM-R displaying an image, an acceleration sensor SS1, aproximity sensor SS2, and a control module CM.

The acceleration sensor SS1 may sense motion of the user US, and thedisplay modules DM-L and DM-R may provide images corresponding to themotion of the user US, to the user US. This may allow the user US toexperience virtual reality content that is similar to the real world.

The proximity sensor SS2 may be used to determine whether a user iswearing the display device HMD. For example, the proximity sensor SS2may be configured to measure a distance to or pressure from a body ofthe user US to determine whether the user US is wearing the displaydevice HMD.

The control module CM may be configured to allow a user to control soundvolume or screen luminance or brightness, and may be provided in theform of a physical button or a touch screen.

The strap portion 200 may be combined with the body portion 100. Thestrap portion 200 may be used to fix the body portion 100 to a head ofthe user US.

The strap portion 200 may include a main strap 210 and an auxiliarystrap 220.

The main strap 210 may be worn along the head circumference of the userUS. The main strap 210 may be configured to bring the body portion 100into close contact with the head of the user US. The auxiliary strap 220may be disposed along a top portion of the head of the user US toconnect the body portion 100 to the main strap 210. The auxiliary strap220 may prevent the body portion 100 from sliding downward when beingworn by the user US. In addition, the auxiliary strap 220 may disperse aweight of the body portion 100, which may improve the comfort of theuser US when the user US is wearing the display device HMD.

The structures or shapes of the body portion 100 and the strap portion200 may be variously changed from those shown in FIGS. 1 and 2 , as longas they can be used to fix the display device HMD to the user US. In anexemplary embodiment, the display device HMD may be provided in the formof a helmet or glasses.

The cushion portion 300 may be disposed on a surface of the body portion100. The surface may be a surface facing the user US when the displaydevice HMD is worn on the user US. The cushion portion 300 may include afreely deformable material. For example, the cushion portion 300 mayinclude a polymer resin. As an example, the cushion portion 300 mayinclude polyurethane, polycarbonate, polypropylene, or polyethylene, ormay include a sponge, which is formed by blowing a rubber solution,urethane-based materials, or acryl-based materials. However, thematerials of the cushion portion 300 are not limited to these examples.

The cushion portion 300 may allow for improved comfort of the displaydevice HMD when worn by the user US. The cushion portion 300 may beconfigured to be attachable or detachable to or from the body portion100. In an exemplary embodiment, the cushion portion 300 may be omitted.

FIG. 3 exemplarily illustrates the body portion 100, the cushion portion300, and the display modules DM-L and DM-R of the display device HMDshown in FIG. 1 .

Referring to FIG. 3 , the display modules DM-L and DM-R may include aleft-eye display module DM-L and a right-eye display module DM-R. FIG. 3illustrates an example of the display device HMD including two displaymodules DM-L and DM-R. However, the inventive concept is not limited tothis example. For example, in an exemplary embodiment, the displaydevice HMD may be configured to include only one display module. Thatis, in an exemplary embodiment, the left-eye display module DM-L and theright-eye display module DM-R may be provided in the form of a singledisplay module.

Each of the display modules DM-L and DM-R may include a display region,which is used to provide an image to the user US (e.g., see FIG. 2 ) andis parallel to a plane defined by a first direction DR1 and a seconddirection DR2. A direction normal to the display region (e.g., athickness direction of each of the display modules DM-L and DM-R) willbe referred to as a third direction DR3.

Two openings OP-L and OP-R may be defined in a region of the bodyportion 100. The openings OP-L and OP-R may include a left-eye openingOP-L and a right-eye opening OP-R. An image displayed on the left-eyedisplay module DM-L may be provided to the user US through the left-eyeopening OP-L, and an image displayed on the right-eye display moduleDM-R may be provided to the user US through the right-eye opening OP-R.

Since the left-eye display module DM-L and the right-eye display moduleDM-R provide independent image information to left and right eyes of theuser US, the user US may recognize an image provided from the displaymodules DM-L and DM-R as a three dimensional image.

FIG. 4A illustrates an exemplary planar structure of a portion of thedisplay modules DM-L and DM-R according to an exemplary embodiment ofthe inventive concept. FIG. 4B is a cross-sectional view taken alongline I-I′ of FIG. 4A. FIG. 5 is an enlarged view of region ‘AA’ of FIG.4B. FIGS. 6A and 6B are graphs exemplarily showing a change in luminanceor brightness of a pixel region AR caused by a variation in depth of anintaglio pattern in a cover layer.

Referring to FIG. 4B, each of the display modules DM-L and DM-R mayinclude a planarization layer PL, a plurality of light-emitting elementsLD1, LD2, and LD3, a pixel definition layer PDL, and a sealing elementECP.

The planarization layer PL may include an organic material or aninorganic material.

The plurality of light-emitting elements LD1, LD2, and LD3 may bedisposed on the planarization layer PL. The light-emitting elements LD1,LD2, and LD3 may emit light having colors that are different from eachother. For example, a first light-emitting element LD1 may emit lighthaving a first color, a second light-emitting element LD2 may emit lighthaving a second color different from the first color, and a thirdlight-emitting element LD3 may emit light having a third color differentfrom the first and second colors.

The first light-emitting element LD1 may emit a red light. The firstlight-emitting element LD1 may include an anode ADE, a hole controlregion HTR, a first emission layer EML1, an electron control region ETR,and a cathode CTD.

In a case in which the first emission layer EML1 emits a red light, thefirst emission layer EML1 may include, for example, a fluorescentmaterial includingPBD:Eu(DBM)3(Phen)(tris(dibenzoylmethanato)phenanthoroline europium) orPerylene. Dopants included in the first emission layer EML1 may beselected from, for example, metal complexes or organometallic complexes,such as PIQIr(acac)(bis(1-phenylisoquinoline)acetylacetonate iridium),PQIr(acac)(bis(1-phenylquinoline)acetylacetonate iridium),PQIr(tris(1-phenylquinoline)iridium), and PtOEP(octaethylporphyrinplatinum).

The second light-emitting element LD2 may emit a green light. The secondlight-emitting element LD2 may include an anode ADE, a hole controlregion HTR, a second emission layer EML2, an electron control regionETR, and a cathode CTD.

In a case in which the second emission layer EML2 emits a green light,the second emission layer EML2 may include, for example, fluorescentmaterials including Alq3(tris(8-hydroxyquinolino)aluminum). Dopantsincluded in the second emission layer EML2 may be selected from metalcomplexes or organometallic complexes, such as Ir(ppy)3(fac-tris(2-phenylpyridine)iridium).

The third light-emitting element LD3 may emit a blue light. The thirdlight-emitting element LD3 may include an anode ADE, a hole controlregion HTR, a third emission layer EML3, an electron control region ETR,and a cathode CTD.

In a case in which the third emission layer EML3 emits a blue light, thethird emission layer EML3 may include, for example, a fluorescentmaterial selected from the group consisting of spiro-DPVBi, spiro-6P,DSB (distyryl-benzene) polymers, DSA (distyryl-arylene) polymers, PFO(Polyfluorene) polymers, and PPV (poly(p-phenylene vinylene) polymers.Dopants included in the third emission layer EML3 may be selected frommetal complexes or organometallic complexes, such as (4,6-F2ppy)2Irpic.

FIG. 4B illustrates an example in which each of the light-emittingelements LD1, LD2, and LD3 is an organic light emitting diode (OLED).However, the inventive concept is not limited to this example. Forexample, in an exemplary embodiment, each of the light-emitting elementsLD1, LD2, and LD3 may be a micro LED.

The sealing element ECP may seal or encapsulate the light-emittingelements LD1, LD2, and LD3, and may protect the light-emitting elementsLD1, LD2, and LD3 from external oxygen or moisture.

The sealing element ECP may include a base part BS and a cover layer CL.A thickness WD-CL of the cover layer CL may be smaller than a thicknessWD-BS of the base part BS. For example, the thickness WD-CL of the coverlayer CL may range from about 100 μm to about 300 μm, and the thicknessWD-BS of the base part BS may range from about 500 nm to about 600 nm.

The base part BS may include a transparent material which allows lightemitted from the light-emitting elements LD1, LD2, and LD3 to passtherethrough. The transparent material may be, for example, glass orplastic.

The cover layer CL may be disposed on a surface of the base part BS. Forexample, the cover layer CL may be disposed directly on the surface ofthe base part BS such that the cover layer CL is in direct contact withthe base part BS. The cover layer CL may include, for example, silicondioxide.

Referring to FIG. 4A, the cover layer CL may include patterns PT-G andPT-B, which diffract light passed through the base part BS.

The patterns PT-G and PT-B may include intaglio patterns PT-G and reliefpatterns PT-B. The intaglio patterns PT-G may be formed or engraved in asurface of the cover layer CL, and in this case, relatively protrudingportions may be defined as the relief patterns PT-B. For example, in anexemplary embodiment, before the intaglio patterns PT-G are formed inthe surface of the cover layer CL, the surface of the cover layer CL maybe substantially flat. Upon engraving the intaglio patterns PT-G intothe surface of the cover layer CL, the engraved portions PT-G may becomerecessed relative to the non-engraved portions, and the non-engravedportions may thus form the protruding portions of the cover layer CLcorresponding to the relief patterns PT-B.

Herein, when a pattern is described as being engraved in an intagliomanner, it is to be understood that the pattern may be formed byincising the pattern into the intended surface.

In an exemplary embodiment, the intaglio patterns PT-G may be formed byusing a photomask (e.g., a slit mask or a half-tone mask).

Referring to FIG. 5 , the intaglio patterns PT-G may include a pluralityof first intaglio patterns PT-G1 and a plurality of second intagliopatterns PT-G2.

In an exemplary embodiment, a distance between centers of two adjacentones of the intaglio patterns PT-G may range from about 3 μm to about 12μm. Each of the first intaglio patterns PT-G1 may be engraved to a firstdepth DH1, and each of the second intaglio patterns PT-G2 may beengraved to a second depth DH2 different from the first depth DH1. In anexemplary embodiment, the second depth DH2 is deeper than the firstdepth DH1. For example, the second depth DH2 may extend further into thesurface of the cover layer CL than the first depth DH1.

The first intaglio pattern PT-G1 and the second intaglio pattern PT-G2may be disposed adjacent to each other. For example, the intagliopatterns PT-G having at least two different depths may be disposed in analternating manner. For example, in an exemplary embodiment, a firstintaglio pattern PT-G1 having the first depth DH1 may be disposeddirectly adjacent to a second intaglio pattern PT-G2 having the seconddepth DH2, and this arrangement may be continuously repeated. As aresult, in an exemplary embodiment, a first intaglio pattern PT-G1 isnever directly adjacent to another first intaglio pattern PT-G1, and asecond intaglio pattern PT-G2 is never directly adjacent to anothersecond intaglio pattern PT-G2. For example, in such an exemplaryembodiment, a first intaglio pattern PT-G1 is always disposed betweentwo second intaglio patterns PT-G2 that are directly adjacent to thefirst intaglio pattern PT-G1 on opposite sides, and a second intagliopattern PT-G2 is always disposed between two first intaglio patternsPT-G1 that are directly adjacent to the second intaglio pattern PT-G2 onopposite sides.

In an exemplary embodiment, each of the first depth DH1 and the seconddepth DH2 may range from about 100 nm to about 200 nm. In an exemplaryembodiment, the second depth DH2 may be greater than the first depthDH1, and a difference between the second depth DH2 and the first depthDH1 may range from about 70 nm to about 90 nm.

Since diffraction of light emitted from the light-emitting elements LD1,LD2, and LD3 is determined by the depths of the intaglio patterns PT-G,optical diffraction caused by the first intaglio patterns PT-G1 of thefirst depth DH1 may be different from optical diffraction caused by thesecond intaglio patterns PT-G2 of the second depth DH2.

Referring to FIG. 6B, the pixel region AR may be a region correspondingto one of the light-emitting elements LD1, LD2, and LD3. The pixelregion AR may include a center region AR-C, which is overlapped with oneof the emission layers EML1, EML2, and EML3, and an edge region AR-E,which is adjacent to the center region AR-C.

Referring to FIG. 6A, a first graph GPH-C is a graph showing a change inluminance of the center region AR-C caused by a change in depth of anintaglio pattern PT-G, and a second graph GPH-E is a graph showing achange in luminance of the edge region AR-E caused by a change in depthof the intaglio pattern PT-G.

Referring to FIGS. 6A and 6B, when a depth of the intaglio pattern PT-Gis a, luminance of the center region AR-C is higher than luminance ofthe edge region AR-E. When the depth of the intaglio pattern PT-G is b,which is larger than a, luminance of the center region AR-C is aboutequal to luminance of the edge region AR-E. When the depth of theintaglio pattern PT-G is c, which is larger than b, luminance of thecenter region AR-C is lower than luminance of the edge region AR-E. Whenthe depth of the intaglio pattern PT-G is d, which is larger than c,luminance of the center region AR-C is about equal to luminance of theedge region AR-E. When the depth of the intaglio pattern PT-G is e,which is larger than d, luminance of the center region AR-C is higherthan luminance of the edge region AR-E.

The difference in luminance between the center region AR-C and the edgeregion AR-E may result from a change in optical diffraction, which iscaused by a change in depth of the intaglio pattern PT-G. Thus, thedepth of the intaglio pattern PT-G may be determined based on thedifference in luminance between the center region AR-C and the edgeregion AR-E. For example, the depth of the intaglio pattern PT-G may bedetermined to be the value of b or d (e.g., see FIG. 6A), at which theluminance of the center region AR-C is about equal to the luminance ofthe edge region AR-E, which may improve display characteristics (e.g.,by providing more uniform luminance across the center region AR-C andthe edge region AR-E).

In the actual process of forming the intaglio pattern PT-G, it may bedifficult to form the intaglio pattern PT-G at a uniform depth of b ord. Thus, in practice, similar to the case of the depth of a or e, theremay be a difference in luminance between the center region AR-C and theedge region AR-E, even when forming the intaglio pattern PT-G at a depthof b or d. Thus, to reduce the difference in luminance between thecenter region AR-C and the edge region AR-E, a plurality of intagliopatterns PT-G having depths different from each other may be formed in asurface of the cover layer CL, as shown in FIGS. 4B and 5 .

In an exemplary embodiment, the intaglio patterns PT-G may be formed insuch a way that a difference in depth between patterns is about equal toa difference between b and d. For example, in an exemplary embodiment,the intaglio patterns PT-G may be formed such that a difference in depthbetween patterns corresponds to the difference between two differentdepths at which luminance of the center region AR-C and the edge regionAR-E is about equal (e.g., points b and d in FIG. 6A). Here, thedifference between b and d may range from about 70 nm to about 90 nm.This is a range which can effectively reduce or compensate thedifference in luminance between the center region AR-C and the edgeregion AR-E, but is not within a typical range of process error.

Hereinafter, a structure shown in FIG. 5 (in particular, the reliefpatterns PT-B) will be described in more detail below.

The cover layer CL may include a base layer BL and the relief patternsPT-B. The base layer BL may be in contact with the base part BS. Forexample, the base layer BL may directly contact the base part BS.

In an exemplary embodiment, the base layer BL may have a thicknessranging from about 250 nm to about 400 nm.

The relief patterns PT-B may include first relief patterns PT-B1, secondrelief patterns PT-B2, and third relief patterns PT-B3.

The first relief patterns PT-B1 may protrude from the base layer BL by afirst length LL1. The first relief patterns PT-B1 may be spaced apartfrom each other by a first distance DT1. In an exemplary embodiment, thefirst length LL1 may range from about 70 nm to about 90 nm. In anexemplary embodiment, the first distance DT1 may range from about 1.5 μmto about 7.5 μm.

In an exemplary embodiment, a width WD1 (hereinafter, a first width) ofeach of the first relief patterns PT-B1 may range from about 4 μm toabout 20 μm.

Each of the second relief patterns PT-B2 may protrude from a firstportion of a corresponding first relief pattern PT-B1 by a second lengthLL2. In an exemplary embodiment, the second length LL2 may range fromabout 10 nm to about 130 nm.

Each of the third relief patterns PT-B3 may protrude from a secondportion of a corresponding first relief pattern PT-B1 by the secondlength LL2. Thus, in an exemplary embodiment, each first relief patternPT-B1 may have both a second relief pattern PT-B2 and a third reliefpattern PT-B3 extending therefrom.

In an exemplary embodiment, the second length LL2 may have about thesame value as the first depth DH1, and a sum of the first length LL1 andthe second length LL2 may be about the same value as the second depthDH2.

In an exemplary embodiment, a width WD2 (hereinafter, a second width) ofeach of the third relief patterns PT-B3 may range from about 1 μm toabout 6 μm.

Each of the second relief patterns PT-B2 may be spaced apart from acorresponding one of the third relief patterns PT-B3 by a seconddistance DT2. In an exemplary embodiment, the second distance DT2 mayrange from about 1.5 μm to about 7.5 μm. In an exemplary embodiment, thefirst distance DT1 may be substantially equal to the second distanceDT2.

FIGS. 7 and 8 are cross-sectional views each illustrating an example ofa modified structure of region ‘AA’ of FIG. 5 .

Referring to region AA-1 of FIG. 7 , intaglio patterns PT-G0 may includefirst intaglio patterns PT-G1, second intaglio patterns PT-G2, and thirdintaglio patterns PT-G3.

Each of the first intaglio patterns PT-G1 may be engraved to a firstdepth DH1, each of the second intaglio patterns PT-G2 may be engraved toa second depth DH2 different from the first depth DH1, and each of thethird intaglio patterns PT-G3 may be engraved to a third depth DH3different from the first depth DH1 and the second depth DH2.

In an exemplary embodiment, each of the first depth DH1, the seconddepth DH2, and the third depth DH3 may range from about 100 nm to about200 nm.

In an exemplary embodiment, the third depth DH3 may be larger than thefirst depth DH1, and the second depth DH2 may be larger than the thirddepth DH3. Here, a difference between the first depth DH1 and the seconddepth DH2 may range from about 70 nm to about 90 nm.

In an exemplary embodiment, the largest difference between the firstdepth DH1, the second depth DH2, and the third depth DH3 may range fromabout 70 nm to about 90 nm. In an exemplary embodiment, the plurality offirst intaglio patterns PT-G1, the plurality of second intaglio patternsPT-G2, and the plurality of third intaglio patterns PT-G3 may bealternatingly disposed. For example, as shown in FIG. 7 , a secondintaglio pattern PT-G2 may be disposed between a first intaglio patternPT-G1 and a third intaglio pattern PT-G3, and this arrangement may becontinuously repeated.

The first intaglio pattern PT-G1, the second intaglio pattern PT-G2, andthe third intaglio pattern PT-G3 may be disposed adjacent to each other.For example, the intaglio patterns PT-G0 having depths different fromeach other may be alternatingly disposed.

Referring to region AA-2 of FIG. 8 , intaglio patterns PT-G10 mayinclude first intaglio patterns PT-G11 and second intaglio patternsPT-G12.

In the cover layer CL, an inner side surface SF defining each of thefirst intaglio patterns PT-G11 and the second intaglio patterns PT-G12may be inclined at an angle of θ_(f) about 60° to about 85°, relative tothe base layer BL or the base part BS. In an exemplary embodiment, theinner side surfaces SF defining each of the first intaglio patternsPT-G11 and the second intaglio patterns PT-G12 may be inclined inwardtoward the center of the corresponding intaglio pattern.

Except for these differences, the structure of FIG. 8 may be configuredto have substantially the same structure as that of FIG. 5 , and forconvenience of explanation, a further description thereof will beomitted.

FIG. 9 illustrates an exemplary planar structure of a portion of displaymodules DM-R1 and DM-L1 according to an exemplary embodiment of theinventive concept.

Referring to FIG. 9 , the intaglio patterns PT-G of the display modulesDM-R1 and DM-L1 may be arranged in a direction that is inclined at anangle of θ_(p) to the second direction DR2. The angle θ_(p) may rangefrom about 5° to about 50°.

FIGS. 10 and 11 are cross-sectional views taken along line I-I′ of FIG.4A.

Referring to FIG. 10 , the light-emitting elements LD1, LD2, and LD3 maybe sealed or encapsulated by a sealing element ECP-1. The sealingelement ECP-1 may include a thin film encapsulation layer TFE and acover layer CL-1.

The thin film encapsulation layer TFE may be in contact with thelight-emitting elements LD1, LD2, and LD3 and may cover thelight-emitting elements LD1, LD2, and LD3.

The thin film encapsulation layer TFE may include a first inorganiclayer CVD1, an organic layer MN, and a second inorganic layer CVD2. Theorganic layer MN may be disposed between the first inorganic layer CVD1and the second inorganic layer CVD2. FIG. 10 illustrates an example inwhich the thin film encapsulation layer TFE includes two inorganiclayers and one organic layer. However, the inventive concept is notlimited to this example. For example, the thin film encapsulation layerTFE may include three inorganic layers and two organic layers, and inthis case, the inorganic layer and the organic layers may have analternatingly-stacked structure.

In an exemplary embodiment, the cover layer CL-1, in which patterns PT-Band PT-G are defined, may be directly disposed on the thin filmencapsulation layer TFE.

Except for these differences, the cover layer CL-1 of FIG. 10 may beconfigured to have substantially the same features as those of the coverlayer CL in the previously described exemplary embodiments.

Referring to FIG. 11 , the light-emitting elements LD1, LD2, and LD3 maybe sealed or encapsulated by a thin film encapsulation layer TFE-1.

The thin film encapsulation layer TFE-1 may include the first inorganiclayer CVD1, the organic layer MN, and a second inorganic layer CVD2-1.The organic layer MN may be disposed between the first inorganic layerCVD1 and the second inorganic layer CVD2-1.

The patterns PT-B and PT-G may be defined in the second inorganic layerCVD2-1.

The patterns PT-B and PT-G of the second inorganic layer CVD2-1 may beconfigured to have substantially the same function as the patterns PT-Band PT-G described with reference to FIGS. 4A to 10 .

As is traditional in the field of the inventive concept, exemplaryembodiments are described, and illustrated in the drawings, in terms offunctional blocks, units and/or modules. Those skilled in the art willappreciate that these blocks, units and/or modules may be physicallyimplemented by electronic (or optical) circuits such as logic circuits,discrete components, microprocessors, hard-wired circuits, memoryelements, wiring connections, etc.

According to an exemplary embodiment of the inventive concept, a displaydevice which can suppress a reduced screen-door effect (SDE), and ahead-mounted display device including the same, may be realized.

Accordingly, a display device having improved display quality andvisibility, and a head-mounted display device including the same, may beprovided according to an exemplary embodiment of the inventive concept.

While the inventive concept has been particularly shown and describedwith reference to the exemplary embodiments thereof, it will beunderstood by one of ordinary skill in the art that variations in formand detail may be made therein without departing from the spirit andscope of the inventive concept as defined by the following claims.

What is claimed is:
 1. A display module, comprising: a plurality oflight-emitting elements; and a sealing element sealing the plurality oflight-emitting elements, wherein the sealing element comprises: a basepart comprising a transparent material; and a cover layer in contactwith a surface of the base part, wherein the cover layer comprises aplurality of first patterns, each of which is engraved in an intagliomanner to a first depth, and a plurality of second patterns, each ofwhich is engraved in the intaglio manner to a second depth differentfrom the first depth, wherein the first patterns form recesses having abottom surface formed at the first depth and opposing side surfaces inthe cover layer, the second patterns form recesses having a bottomsurface formed at the second depth and opposing side surfaces in thecover layer, and the bottom surfaces and the opposing side surfacescorrespond to an uppermost surface of the cover layer, wherein the firstpatterns and the second patterns are alternatingly disposed such that,among the bottom surfaces formed at the first depth and the bottomsurfaces formed at the second depth, each bottom surface formed at thefirst depth is directly adjacent to one of the bottom surfaces formed atthe second depth, wherein the first patterns do not contact the basepart, and the second patterns do not contact the base part, wherein athickness of the cover layer is smaller than a thickness of the basepart, and wherein the first patterns are spaced apart from each other bythe same distance, and the second patterns are spaced apart from eachother by the same distance.
 2. The display module of claim 1, whereinthe cover layer comprises silicon dioxide.
 3. The display module ofclaim 1, wherein the thickness of the base part ranges from about 100 μmto about 300 μm, the thickness of the cover layer ranges from about 500nm to about 600 nm, and each of the first depth and the second depthranges from about 100 nm to about 200 nm.
 4. The display module of claim3, wherein the second depth is larger than the first depth, and adifference between the second depth and the first depth ranges fromabout 70 nm to about 90 nm.
 5. The display module of claim 4, whereinthe difference between the second depth and the first depth isdetermined based on a difference in luminance between a center regionand an edge region of a pixel region corresponding to at least one ofthe plurality of light-emitting elements.
 6. The display module of claim1, wherein an inner side surface of the cover layer defining at leastone of the plurality of first patterns and the plurality of secondpatterns is inclined at an angle of about 60° to about 85° relative tothe base part.
 7. A display module, comprising: a plurality oflight-emitting elements; and a sealing element sealing the plurality oflight-emitting elements and comprising a base part comprising atransparent material and a cover layer disposed on a surface of the basepart, wherein the cover layer comprises: a base layer in contact withthe surface of the base part; a plurality of first patterns, each ofwhich contacts and protrudes from the base layer by a first length, andwhich are spaced apart from each other by a first distance; a pluralityof second patterns, each of which contacts and protrudes from a portionof a corresponding one of the plurality of first patterns by a secondlength; and a plurality of third patterns, each of which contacts andprotrudes from another portion of a corresponding one of the pluralityof first patterns by the second length, wherein the second patterns donot contact the base part, and the third patterns do not contact thebase part, wherein the first to third patterns form recesses having afirst bottom surface formed at a first depth and corresponding toportions of upper surfaces of the first patterns and opposing sidesurfaces corresponding to one side surface of each of the second andthird patterns in the cover layer, form recesses having a second bottomsurface formed at a second depth different from the first depth andcorresponding to portions below the upper surfaces of the first patternsand opposing side surfaces corresponding to one side surface of each ofthe second and third patterns in the cover layer, and the bottomsurfaces and the opposing side surfaces correspond to an uppermostsurface of the cover layer, wherein the recesses having the first bottomsurface and the recesses having the second bottom surface arealternatingly disposed such that, among the first bottom surfaces formedat the first depth and the second bottom surfaces formed at the seconddepth, each first bottom surface formed at the first depth is directlyadjacent to one of the second bottom surfaces formed at the seconddepth, wherein a thickness of the cover layer is smaller than athickness of the base part, and wherein the second patterns are spacedapart from each other by the same distance, and the third patterns arespaced apart from each other by the same distance.
 8. The display moduleof claim 7, wherein each of the plurality of second patterns is spacedapart from a corresponding one of the plurality of third patternsprotruding from a same first pattern by a second distance.
 9. Thedisplay module of claim 7, wherein the thickness of the base part rangesfrom about 100 μm to about 300 μm, a thickness of the base layer rangesfrom about 250 nm to about 400 nm, the first length ranges from about 70nm to about 90 nm, and the second length ranges from about 10 nm toabout 130 nm.
 10. The display module of claim 7, wherein a side surfaceof each of the plurality of first patterns or a side surface of each ofthe plurality of second patterns is inclined at an angle of about 60° toabout 85° relative to the base layer.
 11. A head-mounted display device,comprising: a display module comprising a plurality of light-emittingelements and a sealing element sealing the light-emitting elements; abody portion containing the display module, wherein an opening definedin the body portion exposes at least a portion of the display module toa user; and a strap portion connected to the body portion and configuredto fix the body portion to a head of the user, wherein the sealingelement comprises: a base part comprising a transparent material; and acover layer in contact with a surface of the base part, wherein thecover layer comprises a plurality of first patterns, each of which isengraved in an intaglio manner to a first depth, and a plurality ofsecond patterns, each of which is engraved in the intaglio manner to asecond depth different from the first depth, wherein the first patternsform recesses having a bottom surface formed at the first depth andopposing side surfaces in the cover layer, the second patterns formrecesses having a bottom surface formed at the second depth and opposingside surfaces in the cover layer, and the bottom surfaces and theopposing side surfaces correspond to an uppermost surface of the coverlayer, wherein the first patterns and the second patterns arealternatingly disposed such that, among the bottom surfaces formed atthe first depth and the bottom surfaces formed at the second depth, eachbottom surface formed at the first depth is directly adjacent to one ofthe bottom surfaces formed at the second depth, wherein each of thefirst depth of the first patterns and the second depth of the secondpatterns is smaller than a thickness of the cover layer, wherein thethickness of the cover layer is smaller than a thickness of the basepart, wherein the first patterns do not contact the base part, and thesecond patterns do not contact the base part, and wherein the firstpatterns are spaced apart from each other by the same distance, and thesecond patterns are spaced apart from each other by the same distance.12. The head-mounted display device of claim 11, wherein the cover layercomprises silicon dioxide.
 13. The head-mounted display device of claim11, wherein the thickness of the base part ranges from about 100 μm toabout 300 μm, the thickness of the cover layer ranges from about 500 nmto about 600 nm, and each of the first depth and the second depth rangesfrom about 100 nm to about 200 nm.
 14. The head-mounted display deviceof claim 11, wherein the second depth is larger than the first depth,and a difference between the second depth and the first depth rangesfrom about 70 nm to about 90 nm.